Such a switching node was disclosed in the European patent application 0524350 published on Jan. 27, 1993 and corresponding to U.S. Pat. No. 5,309,430, wherein it was proposed to transfer cells to a further node by regularly distributing them over various transmission links connecting the output ports of the group to the further node. In so doing enhanced efficiency of the links between the nodes as well as enhanced reliability of communications on these links is provided.
A problem with this approach is that it does not allow the addressing of groups comprising arbitrarily chosen output ports, but only the addressing of so called regular groups, i.e. groups comprising output ports whose adresses are linked by a mathematical relationship. The addresses of the output ports constituting a regular group thus are for instance of the form ABXDEFXXIJXX where A, B, D, E, G, I and J are specific binary values and X is a symbol representing any binary value, i.e. it is a don't care value.
The above limitation to regular groups arises from the fact that such a node achieves the distribution over such a regular group of output ports by addressing the group with an address as in the above example, i.e. defined with the aid of don't care values, and by letting each switching element finally associate a specific value to these don't care values at the moment it switches a cell. It can thus be easily verified that the above described switching node cannot distribute cells to an irregular group of output ports since such an irregular group rules out the use of random or don't care bit values to identify outlets of a switching element.